favorite We need a little bit of your help to keep things running, click on this banner to learn more

2018 Цикл Интернет-олимпиад для школьников

Greek car

After long journeys and wanderings, in one temple Kratos discovered an interesting find - a Greek car. It was one of the first prototypes that worked on clean energy. In the same temple, Kratos also found fuel - a fountain containing a litres of clean energy.

Kratos knows that 1 litre of clean energy is enough to cover 100 kilometres. However, there is one problem - the tank of the machine is designed so that no more than 1 litres of energy can be placed in it, and energy can only be replenished in the temple. However, having carefully studied the structure of this clean energy, Kratos realised that he could pour off it to the ground and leave it on the ground, and then return and put it into the tank without loss. Now he is interested in the question - what is the maximum distance he can travel on the machine he found?


One real number а (0.0а2.0) - the number of litres of clean energy in the fountain.


Print the maximum distance that Kratos can travel on the machine found. The answer should be displayed with an accuracy of 6 decimal places.

Time limit 1 second
Memory limit 128 MiB
Input example #1
Output example #1
Source 2018 Cycle of Internet Olympiads for schoolchildren, second team season olympiad, Basic nomination, October 20, Problem B